Abstract: Objective It aims to address the outdated radiographic testing technology for the girth welds of launch vehicle tanks under multiple constraints, and to resolve prominent issues such as low inspection efficiency, difficult quality control, cumbersome film storage, and high labor intensity. Methods An automatic digital radiography inspection system was developed by integrating special mechanical designs-including a small-sized rectangular detector, a semi-circular cantilever structure, and a foldable and retractable detector mechanism-with a radiation source, an electrical control system, and inspection software. The proposed system was subsequently verified through experimental inspections. Results The results indicate that the image quality meets the Class A requirements of national standards, the inspection results are accurate, and the inspection efficiency is significantly improved. Conclusion The developed inspection system and the improved RT process ensure the automated, digital, efficient, and high-quality radiographic inspection of tank girth welds under multiple constraints, providing strong support for the rapid and batch manufacturing of launch vehicle tanks.